BACKGROUND Patients-Reported Outcomes (PRO) are increasingly used in clinical and epidemiological research. Two main types of analytical strategies can be found for these data: classical test theory (CTT) based on the observed scores and models coming from Item Response Theory (IRT). However, whether IRT or CTT would be the most appropriate method to analyse PRO data remains unknown. The statis...

We investigated the effect of 8 weeks of high intensity interval training (HIT) and isoinertial resistance training (IRT) on cardiovascular fitness, muscle mass-strength and risk factors of metabolic syndrome in 12 healthy older adults (68 yy ± 4). HIT consisted in 7 two-minute repetitions at 80%-90% of V˙O2max, 3 times/w. After 4 months of recovery, subjects were treated with IRT, which inclu...

Item response theory (IRT) has a number of potential advantages over classical test theory in assessing self-reported health outcomes. IRT models yield invariant item and latent trait estimates (within a linear transformation), standard errors conditional on trait level, and trait estimates anchored to item content. IRT also facilitates evaluation of differential item functioning, inclusion of ...

Figure 1. Salivary gland scintigraphy performed before (March 2005) and after (August 2005) iodine-131 internal radiation therapy (I-131 IRT). Anterior images obtained at 10 and 20 minutes after intravenous injection of Tc-99m, and at 5 minutes after washout by Vitamin C are shown. Original scintigraphy was performed as a dynamic study with 1 min/frame. Significantly higher accumulation was obs...

Item response theory (IRT) models are a class of statistical models used by researchers to describe the response behaviors of individuals to a set of categorically scored items. The most common IRT models can be classified as generalized linear fixedand/or mixed-effect models. Although IRT models appear most often in the psychological testing literature, researchers in other fields have success...

Changes in the skin temperature (Tsk) are known to be connected with diseases and subsequently infrared thermography (IRT) has been proposed to be a diagnostic aid, e.g. in musculoskeletal disorders (MSD). However, mostly due to conflicting results of previous studies, IRT lost credibility. Now interest in IRT is growing again but valid methodological studies are needed in order to avoid new di...

BACKGROUND Item response theory (IRT) has been increasingly applied to patient-reported outcome (PRO) measures. The purpose of this study is to apply IRT to examine item properties (discrimination and severity of depressive symptoms), measurement precision and score comparability across five depression measures, which is the first study of its kind in the Chinese context. METHODS A clinical s...

CONTEXT Newborn screening for cystic fibrosis (CF) is included in many routine programmes but current strategies have considerable drawbacks, such as false-positive tests, equivocal diagnosis and detection of carriers. OBJECTIVE To assess the test performance of two newborn screening strategies for CF. DESIGN, SETTING AND PARTICIPANTS In 2008 and 2009, CF screening was added to the routine ...

In item response theory (IRT) models, assessing model-data fit is an essential step in IRT calibration. While no general agreement has ever been reached on the best methods or approaches to use for detecting misfit, perhaps the more important comment based upon the research findings is that rarely does the research evaluate IRT misfit by focusing on the practical consequences of misfit. The stu...

This paper applies the techniques of Item Response Theory (IRT) to data from the Statistics Concept Inventory (SCI). Based on results from the Fall 2005 post-test (n = 422 students), the analyses of IRT are compared with those of Classical Test Theory (CTT). The concepts are extended to discussions of other applications, such as computerized adaptive testing and Likertscale items which may be o...